It depends where you live. For my family we ususally open our inground pool when summer first starts (maybe around the middle of June or anytime in July). It really depends on how hot the temeperature is where you live and and when the weather is hot enough. It is really up to you. This year though we weren't able to open our pool due to the bad weather we experienced.
Read the owners manual.
The first thing you should keep in mind is the possibility of corrosion and the buidup of ground water around the outside of the pool.
Open
You can. but you should not leave an in ground pool empty for any period of time. Ground water building up around it is capable of even lifting an empty concrete pool out of the ground.
An in ground pool and an above ground pool have difference maintenance requirements. You should start by researching the time and effort it would take to maintain them. Then make your decision based on your research.
i think its up
You can expect to pay at least $1000 for an above ground, and more for an in ground. It also depends on the size of the pool.
Buying a cover for the pool should take care of the situation. As long as it fits the pool properly
It should be on "FILTER"
NO however you should keep in mind that the ground water outside of the pool is not going to put pressure on it as this is capable of even lifting a concrete pool out of the ground.
No , above ground pools are different in that you can drain them , the reason you cannot drain an in ground pool is because the pool is built to have water pressure , and it is very stressful on the walls , I hope this answered your question :) .
It depends on the diameter and depth of the pool. It should say on the box.